Characterization of the Unique Viscoelastic Properties of the Mitral Valve Anterior Leaflet

Abstract

The most common mitral valve (MV) disease is the MV regurgitation, in which the anterior leaflet and the posterior leaflet cannot coapt well and hence result in the leaking of blood from the left ventricle to the left atrium during the systolic phase. The treatment options include MV replacement and repair. In order to develop a bioprosthetic or a tissue engineered mitral valve leaflets that behaves similarly to the native MV, the mechanical properties of the native MV leaflets must be well understood (Grashow et al., 2006). In this study, we aim to characterize the unique viscoelastic properties of mitral valve anterior leaflet by studying the mechanical behavior of the tissue in regards to stress‐relaxation, creep, and tissue failure. Mitral valve anterior leaflets (MVAL) of porcine specimens were obtained from a local abattoir. These specimens were then further dissected in the circumferential direction into a dog‐bone shape samples for mechanical testing at a target load level of 600 grams. The testing protocol for each sample was performed as follows: after preconditioning, leaflet tissue was subjected to (1) stress‐relaxation for 15 minutes, followed by (2) creep for 15 minutes, and finally (3) the sample is ultimately pulled to failure. All testing was performed in a PBS bath using a Test Resources uniaxial testing machine. We observed a normal degree of stress relaxation similar to other types of collagenous tissues (~30% – 50%), but negligible creep. Understanding the unique viscoelastic properties of the native MV leaflets at different loading levels would help to better design bioprosthetics or tissue engineered mitral valves that mimics the natural design and the optimal tissue behavior.Support or Funding InformationThis research was funded by the National Science Foundation Award No. DMR‐1359437 at the Agricultural and Biological Engineering Department at Mississippi State University.Special thanks to Sourav Patnaik and Xiaodan Shi for their contribution to the project and to the UPR‐PRISE Program NIH Grant #R25GM096955 for funding and supporting its students through participation in research experiences during their summer internships